A synchronous reluctance type rotary electric machine includes a rotor and a stator. The rotor includes a shaft rotatably supported and extending in an axial direction with a rotation axis as a center, and a rotor core externally fitted and fixed to the shaft. The stator is disposed to be spaced apart from the rotor core around an outer circumference of the rotor core. The stator includes a stator core having a plurality of teeth disposed at intervals in a circumferential direction and includes multipole multiphase armature windings respectively wound around the plurality of teeth.
A plurality of hollow parts are formed to be aligned in a radial direction for each pole in the rotor core. Each of the hollow parts is formed to be curved toward the radially inner side such that a pole center thereof is positioned furthest inward in the radial direction to follow a flow of magnetic flux formed when the armature windings are energized in many cases.
When the hollow parts are formed in this manner, a direction in which magnetic flux easily flows and a direction in which magnetic flux does not readily flow are formed in the rotor core. With such a configuration, the synchronous reluctance type rotary electric machine rotates the shaft using a reluctance torque generated by the hollow parts.
Incidentally, slots formed between the teeth of the stator core are portions in which magnetic flux does not readily flow. Therefore, a magnetic flux density changes rapidly between the teeth and the slots (hereinafter, this rapid change in the magnetic flux density is referred to as magnetic irregularities of the stator). On the other hand, the rotor core also has a plurality of portions in which the magnetic flux density changes rapidly due to the hollow parts formed to generate a reluctance torque (hereinafter, this rapid change in the magnetic flux density is referred to as magnetic irregularities of the rotor). Thus, torque ripple is generated by an interaction between the magnetic irregularities of the stator and the magnetic irregularities of the rotor. Also, there is a likelihood that the torque ripple increases when the magnetic irregularities of the stator core and the magnetic irregularities of the rotor core resonate.